Goods are shipped all over the world using rectangular steel shipping containers. The shipping container is generally standardized at 20 or 40 feet long, 8-9.5 feet tall, and 8 feet wide, with the walls made of corrugated steel typically 14 gauge thick. The corrugations are also standardized and are angular, with flat peaks and valleys and angled sections joining the flat regions. Excess shipping containers are available for a modest price, and there is great interest in using them as buildings such as sheds, garages, bans, storage rooms, as small houses, or joined in multiples to form larger houses.
A problem with using shipping containers as a house is that the steel wall readily conducts heat or cold. A feature of the shipping container is that it is waterproof, which can be good or bad. When using a shipping container as a house the user typically insulates the wall for comfort. One way to insulate the wall of the shipping container is to attach 2×4 studs to the inside of the wall, and place fiberglass insulation batting between the studs, in the same manner that conventional houses are insulated. A disadvantage of this method is that the process usually involves drilling holes in the shipping container walls for securing the studs. A big disadvantage is that this method basically requires building a stud wall inside the steel wall, thereby negating the benefit of already having a structural wall available. One might as well just build a stick built house in such a case, and forego the shipping container. Drilling holes in the steel wall has the disadvantage of introducing sites of water leakage and rust into the wall, thus decreasing the lifespan of the shipping container. This method of insulating a shipping container is labor intense, and it would be desirable to simplify the process.
Another method of insulating the shipping container wall is to use spray on foam for form an inner coating. The foam forms a rough uneven surface, and is generally unsightly. One way to overcome this is to first attached studs or firring strips to the inner surface of the container wall, and use the edges of the firring strips to smooth the spray on foam.
Another way to insulate the walls of the shipping container is to attach sheets of extruded polystyrene (Styrofoam) to the corrugated steel. The problem with this is that the process leaves air spaces or voids in the corrugations, which can be a source of humidity, rust and mold.
An improved method would be less labor intensive, fill all voids in the corrugations, and not result in penetrations or drilling of the steel container walls.